How do you factor #x^2 + 3x -5x^2 - 15#?

1 Answer
Nghi N.
May 19, 2015

Please check the question?

#y = -4x^2 + 3x - 15.#

This trinomial can't be factored because D = b^2 - 4ac < 0.

The correct question should be: factor # y = x^3 + 3x - 5x^2 - 15.#
To factor, group the first term and the second term together:

#y = x(x^2 + 3) - 5(x^2 + 3) = (x^2 + 3)(x - 5)#

Check by developing:# y = x^3 - 5x^2 + 3x - 15.# OK

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